Quarantine is enforced in accordance with the International Health
Vessels entering Spanish territorial waters from abroad should display
international quarantine signals and have no communication with the shore
until they have been visited by the port health authorities and granted
Radio advice to the health authorities is not required unless there is
contagious sickness on board or if coming from an epidemic zone. Vessels
having a case or a suspected case of infectious disease on board should
also make the appropriate signal in the International Code.